atm-1022 mechanical workshop module 3

8/11/2019 Atm-1022 Mechanical Workshop Module 3

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Mechanical Workshop

Module 3: Marking out and Hand Tools

PREPARED BY

IAT Curriculum Unit

January 2010

Institute of Applied Technology, 2010


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ATM-1022 Mechanical Workshop

Module 3: Marking out and hand tools2

Module 3: Marking out and Hand Tools

Module Objectives

After the completion of this module, student should be able to:

1. Identify different marking out tools and their usage.

2. Select the appropriate tool required for marking out.

3. Mark out workpieces according to the dimensions given in engineering

drawings.4. Identify the different hand tools and their uses.

5. Identify and select the correct tool for the task.

6. State the care and safe use of hand tools.

Module Contents

1 Introduction to marking out 3

2 Common marking out tools 3

3 Practical Task 8

4 Introduction to hand tools 10

5 Worksheet 17


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Module 3: Marking out and hand tools 3

3.1. Introduction to marking out

Marking out is the process of transferring a design, layout or dimensions from

the plan to a workpiece, and it is considered as the first step in the

manufacturing process.3.2. Common marking out tools

The common tools used for marking out

are as follows:

1. Marking blue

2. Scriber

3. Punch

4. Engineers square

5. Surface plate

6. Surface gauge

7. Angle plate

8. Vee block

9. Spring dividers

10. Ball peen hammer

1. Marking blue.

Marking blue is a dye used in

metalworking to aid in marking out.

See Fig. 3.1a. It is used to paint a

metal object with a very thin layer of

dye that can be scratched off using a

scriber to show the bright metal

underneath as shown in Fig. 3.1b.

The advantages of using the marking

blue are:

The existing scratches are covered

with the dye.

The new lines have a contrasting

background.

(a)

(b)

Fig. 3.1: (a) Marking blue layoutdye. (b) Using of marking blue for

marking out.


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2. Scriber

Scribers are used in metalworking to mark lines on workpieces prior to

manufacturing. They are used instead of pencils as the marks from

pencils can rub off easily. They consist of a rod of steel that has been

sharpened to a point at one or both ends. Scribers are used to draw

shallow scratches on the surfaces of the workpieces.

There are two types of scribers:

A)One-end scriber as shown in

Fig. 3.2a.

B)Double-end scriber as shown in

Fig. 3.2b.

(a)

(b)

Fig 3.2: (a) One-end scriber (b)Double-end scriber.

3. Punch

A punch is a hard metal rod with a shaped tip at one end and a rounded

butt at the other end that is usually struck by a hammer.

There are many types of punches,

and the most commonly used onesfor marking out are:

A)Center punch: It is used as an

aid to drilling operations. A center

punch forms an indent in which

the tip of the drill will fit. A center

punch has a point angle of 90 as

shown in Fig. 3.3a.

Fig 3.3a: Center punch

90


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B)Prick punch: It is used for

layout. A prick punch produces a

smaller indentation than a center

punch, which acts as a useful

datum point in layout operations.

A prick punch has a point angle of

60 as shown in Fig.3.3b.

C)Letter stamps or number

stamps: These are used to print a

letter or number into a workpiece.

See Fig.3.3c.

(b)

(c)

Fig 3.3: (b) Prick punch (c) Letter

stamp set

4.Engineers square

The engineers square is shown in

Fig. 3.4. It is used for checking the

straightness of a workpiece. It can

also be used for marking

perpendicular lines onto a workpiece.

Fig 3.4: Engineers square.

5.Surface plate

The surface plate is shown in Fig 3.5.

It has a high degree of flatness. The

flat surface is being used as a datum

surface for marking out and formeasuring purposes. it is also called

surface table If it can stand on the

floor.

Fig 3.5: Surface plate

60


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5.1 Care to the surface plate

YOU MUST

1. Keep the surface in a good condition.

2. Keep the surface lightly oiled to prevent corrosion.

3. Take care when placing marking out tools on the surface.

YOU DO NOT

1. Place anything on the surface that would damage it.

2. Drop tools on the surface.

3. Hammer on the surface.

6. Surface gauge

A surface gauge shown in Fig 3.6 is

used on surface plates for scribing

lines on work pieces and checking

parallel surfaces and heights as

shown inFig 3.6b.

(a)

(b)

Fig 3.6: (a)Surface gauge (b) setting the height of the surface gauge.


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7. Angle plate

The angle plate shown in Fig 3.7 is

used to assist in holding the

workpiece perpendicular to the table.

The angle plate is provided with

holes and slots to enable the secure

attachment or clamping of

workpieces.Fig 3.7: Angle plate

8. Vee block

The Vee blocks shown in Fig 3.8 are

generally used for holding circular

workpieces for marking out or

machining.

Fig 3.8:Vee blocks set

9. Spring dividers

The spring dividers shown in Fig 3.9aare used for scribing arcs and circles

as shown in Fig. 3.9bor marking off

lengths onto a workpiece. (a)

(b)Fig. 3.9:(a) Spring dividers(b) Spring Dividers in use.


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130

80

102

98

Reference Plane

6460

Filling lines

Hack sawinglines

All Dimensions are in mm

Fig 3.11:The filling and hack sawing lines.

2. Marking out the Fillets.See Fig.3.12.

A) Locate and scribe centers for fillets.

B) Punch the centers by using a prick punch.

C)

Scribe the fillets by using spring dividers.

98

Reference Planelines

60

4

4

This fillet is repeated for all corners

R 4

All Dimensions are in mm

Fig 3.12:Shows the fillets arcs


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3. Marking out for drilling. See Fig.3.13.

A) Locate and scribe lines for holes centers using the same

procedure used for scribing the hack sawing and filing lines.

B)

Punch the intersection of the lines by using a center punch.

98

60

12.25

20

14

12.25

14

20

Fig 3.13:The lines for holes centers.

3.4 Introduction to hand tools

The mechanical engineer very often have to use a number of various hand

tools in the course of his duties as a fitter or machinist, many of these

tools are common to both.


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3.4.1 Spanners/Wrenches

In British English spanner and in

American English wrench

describe the same tool.

Spanners/Wrenches are different in

shape to provide ease of operation

under certain conditions. They are

manufactured from high tensile or

alloy steel. The sizes of metric

spanners are identified by the

distance across flats of a nut or

bolt head as shown in Fig 3.14.

S= 24 mm

Fig. 3.14: Distance across flats (s)

3.4.1.1 Spanner Types

1-Open-ended spanners

The ends of this type of spanners are

generally oriented at an angle of 15

to the longitudinal axis of the handle

to allow greater range of movement

in enclosed spaces. Fig. 3.15 shows

open ended spanners of different

sizes.

Fig. 3.15: Open-ended spanners

2-Ring spanners

Ring spanners or box-end wrenches

are recommended to be used when a

better grip is needed and when the

spanner swing is restricted. Fig. 3.16

shows ring spanners of different

sizes.Fig. 3.16: Ring spanners


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3-Combination spanners

This type comes with an open end

from one side and a ring end from

the other side and usually both ends

are having the same size. Fig. 3.17

shows a combination spanner.

Fig. 3.17: Combination spanner

4-Adjustable spanners

Adjustable spanners are spanners

that have a moving jaw to fit

different bolt/nut sizes. Fig. 3.18

shows an adjustable spanner. Fig. 3.18: Adjustable spanner

3.4.1.2 Accidents Prevention

When working with spanners, accidents are usually caused by the slipping

of a spanner from a nut or bolt head and in order to avoid that the

following should be taken into consideration:

Use the correct size spanner for the job.

Pull towards the body whenever possible.

Do not obtain extra leverage by using pieces of pipe.

Use a steady pull not a jerking action. Do not hit a spanner with a hammer.

Make sure your hands will not strike any obstructions.

3.4.2 Allen keys

They are referred to as Allen keys

and sometimes Allen wrenches (Fig.

3.19a). Allen keys are used on socket

head cap screws (Fig. 3.19c) and

grub screws (Fig. 3.19b). The size of

Allen keys is measured across flats.

(a)

(b) (c)Fig. 3.19: (a) Allen keys (b) Grubscrew (c) Socket head cap screw


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3.4.3 Screwdrivers

Screwdrivers (Fig. 3.20a) are made

in different lengths and designs, the

two most common are:

1. Flathead/slotted

2. Crosshead/Phillips

The flathead (Fig. 3.20b) is identified

by its length and in some cases by

the blade width. The crosshead (Fig.

3.20b) screwdriver is identified by its

point size. Always use the correct

size screwdriver for the screw head;

the blade should fit the width of the

screw head.

(a)

Flathead Crosshead(b)

Fig. 3.20: (a) Different types ofscrewdrivers. (b) Flathead andCrosshead.

3.4.4 Pliers

Pliers are a hand tool used to hold objects firmly, or for cutting and

bending tough materials such as wires. There are different types such as

flat nose pliers, long nose pliers, combination pliers and circlip pliers.

These types are designed to deal with different types of jobs.

1- Flat nose pliers

These are used to hold pins and

small objects when working in

confined spaces. Fig. 3.21 shows a

flat nose pliers.

Fig. 3.21: Flat nose pliers.


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2- Long nose pliers

Long nose pliers (Fig. 3.22) are both

cutting and gripping pliers used by

electricians and other tradesmen to

bend, re-position and cut wire.

Fig. 3.22: Long nose pliers.

3- Combination pliers

These pliers (Fig. 3.23) incorporate

side cutters, joint cutters and pipe

grip.Fig. 3.23:Combination pliers

4- Circlip pliers

Circlips are retaining devices (Fig. 3.24). They are fitted inside a grooveon bores and shafts. The internal circlip (Fig. 3.24 a) has to be squeezed

to be removed and the external circlip (Fig. 3.24 b) which is fitted onto a

shaft has to be opened out to be removed. Fig. 3.25 shows internal and

external circlip pliers. The nose is either straight or bent depending on the

type of job.

(a) (b)

Fig.3.24: (a) Internal circlip

(b) External circlip(a) (b) (c) (d)

Fig. 3.25:(a) Straight internal

circlip pliers. (b) Bent nose

external circlip pliers. (c) Bent

nose internal circlip pliers. (d)

Straight external circlip pliers.


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3.4.5 Pipe wrench

A pipe wrench is designed to tighten

its grip on the part being rotated. It

has serrated jaws that leave marks

on the part and so it might damage

the surface of the part. Accordingly,

pipe wrenches must not be used to

loosen a nut, unless the nut is to be

replaced. Fig. 3.26 shows a pipe

wrench.

Fig. 3.26:Pipe wrench


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Students notes

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2. Match the following.

a. Match the marking out tools in column B with their correct functions

in column A, Write your answer in the box below?

Column A 1 2 3 4 5

Column B

Column A Column B

1) Is used for checking the

straightness of a workpiece.

A)

2) Is used to scratch lines

B)

3) Is used for making indents that

position the drill points and stop

them slipping

C)

4) Is used for supporting or

setting up work vertically.D)

5) Is used for scratching lines

parallel to a surface.

E)


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b. Match the hand tools in column B with their correct names in column A,

Write your answer in the box below?

Column A 1 2 3 4 5 6 7 8

Column B

Column A Column B

1) CombinationpliersA)

2) Adjustable spanner

B)

3) Allen key

C)

4) Crosshead screwdriver

D)

5) Open-ended spanner

E)

6) Ring spanner

F)

7) Pipe wrench

G)

8) Flathead screwdriver

H)

atm-1022 mechanical workshop module 3

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